Update count mismatch - internal error

Hi,

While working on polishing remaining upsert issues I found a, afaics
unrelated, issue:

postgres[14993][1]=# CREATE TABLE mismatch(a int, b int);
CREATE TABLE
postgres[14993][1]=# UPDATE mismatch SET a = mismatch.*;
ERROR: XX000: UPDATE target count mismatch --- internal error
LOCATION: transformUpdateTargetList, analyze.c:2103

Seems to be a longer standing thing, going at least back to 9.0.

Greetings,

Andres Freund